1. Field of the Invention
The present invention relates to a switch such as an inhibitor switch.
2. Description of the Related Art
An inhibitor switch device of this kind of the related art is exemplified in Unexamined Published Japanese Patent Application No. 10-134672, as show in FIG. 11. This inhibitor switch 201 is provided with a plurality of stationary contacts 205 on the lower face of a pole board 203, and a moving contact 209 is supported on a moving board 207 which can move with respect to the pole board 203. The moving contact 209 is provided with a plurality of contact arms 211 in a cantilever shape. Each contact arm 211 slidably contacts with each stationary contact 205 as shown in FIG. 12 by way of example.
Each stationary contact 205 is insert-molded on the pole board 203 made of a resin, and a curved contact portion 213 of the contact arm 211 can slide with respect to the stationary contact 205. Moreover, an ON/OFF switching position 215 by the slide of the moving contact 211 with respect to the stationary contact 205 provides a boundary of the insert molding between the stationary contact 205 and the pole board 203.
In accordance with the movement of the moving board 207, therefore, each contact arm 211 slides in contact with each stationary contact 205 so that the contact/non-contact of the contact arm 211 with respect to the stationary contact 205 are made through the ON/OFF switching position 215 so that the selected ON of each stationary contact 205 can be retained.
In this case, the contact portion 213 of the contact arm 211 is curved to take a substantially linear contacting state with the stationary contact 205. By setting the boundary of the insert molding accurately to decide the ON/OFF switching position 215, therefore, the contact/non-contact of each contact arm 211 with respect to each stationary contact 205 can be accurately switched.
However, there is a problem that it is seriously difficult to adjust the ON/OFF switching position 215 on a mold. In the structure thus far described, more specifically, when the ON/OFF switching position 215 is to be adjusted, it is necessary to scrape the end edge of the stationary contact 205, for example, by {fraction (1/100)} mm and to adjust the insert mold accordingly. This makes it necessary to change both the molds for the pole board 203 and the stationary contacts 205 and makes it seriously difficult to decide the ON/OFF switching position 215 by adjusting the two molds.
At a press molding time of the stationary contacts 205, on the other hand, there are formed sags 219, as shown in FIG. 13A, or burrs 221, as shown in FIG. 13B. Even if the ON/OFF switching position 215 is decided, actual ON/OFF switching positions 223 and 225 are dislocated from the ON/OFF switching position 215 by the sags 219 or the burrs 221. From this point, there arises a problem that it is seriously difficult to adjust the ON/OFF switching position accurately.
On the other hand, there is another switch, as exemplified in Unexamined Published Japanese Utility Model Application No. 61-151214 and shown in FIG. 14 and FIG. 15. This switch 231 is used for the door of a refrigerator, for example. This switch 231 is equipped with an operating knob 233. This operating knob 233 is biased outward by an internal spring. This operating knob 233 is equipped with an associated slide. On this slide, there is retained a moving contact 235. This moving contact 235 provides a contact portion 237 at its leading end. In the switch 231, on the other hand, a pole board 239 is equipped with a stationary contact 241. From the pole board 239, there is protruded an insulator portion 243.
When the operating knob 233 is depressed, therefore, the moving contact 235 slides with the slide so that the contact portion 237 comes into contact with the stationary contact 241, as shown by single-dotted lines, to turn ON the switch. When the depression of the operating knob 233 is released, the moving contact 235 is returned to its original position by the biasing action of the return spring. At this time, the moving contact 235 rides on the insulator portion 243, as shown by solid lines, so that the contact portion 237 of the moving contact 235 floats from the stationary contact 241.
By thus causing the moving contact 235 to float thereby to turn OFF it with respect to the stationary contact 241, the ON/OFF switching position can be set not at the end edge of the stationary contact 241 but over the intermediate portion of the stationary contact 241 to switch ON/OFF relatively accurately.
If the floating structure of the contract portion 237 is merely applied to the inhibitor switch 201, however, there is invited a new problem. In the case of the switch 231 for the door of the refrigerator, more specifically, the moving contact 235 can be stopped at the position shown by the solid lines in FIG. 14. In the case of the inhibitor switch 201, however, there are many portions in which the stationary contacts are arranged on the two sides of the insulator portion 243, and there are repeated operations in which the moving contact 235 rides on the insulator portion 243 and in which its contact portion 237 slides over the insulator portion 243 and again contacts with the next stationary contact. As a result, the contact portion 237 of the moving contact 235 may slide on the protruded insulator portion 253 while receiving a high facial pressure (or a contact pressure) to proceed the wear early. This is especially true when the inhibitor switch is frequently mounted in the mission case of automatic transmission or in a case outside of the mission case. From the aspect of heat resistance and strength, therefore, the pole board may be made of a resin containing glass fibers, and the wear of the contact portion 237 of the moving contact 235
In FIG. 16, the pole board 203 of the inhibitor switch is provided with a contact riding insulator portion 245. The inhibitor switch can be turned ON/OFF irrespective of the end edge position of the stationary contact 205 by the ride on the insulator portion 245, as shown in FIG. 16A. As a wear 213a proceeds on the contact portion 213, as shown in FIG. 16B, however, the mechanical position of the moving contact 235 is shifted, when the moving contact 235 abuts against and rides on the insulator portion 245, leftward of the Drawing to an extent of the extension from a distance L1 before the wear of FIG. 16A to a distance L2 after the wear. As a result, the mechanical position of the moving contact 235 and the contact switching position (i.e., the ON/OFF switching position) are dislocated according to the difference between the distances L1 and L2, i.e., the extension of the wear, and the inhibitor switch may lose durability. On the other hand, large amounts of abrasion powder, as produced in the insulator portion 245, migrate together with the moving contact 209 to cover the stationary contact 205. A contact failure may be caused if the abrasion powder is sandwiched between the stationary contact 205 and the moving contact 209 brought down onto the former.
An object of the present invention is to provide a switch device which can adjust the ON/OFF switching position easily and which can effect an accurate ON/OFF switching and retain durability while suppressing the wear of a moving contact.
According to a first aspect of the invention, there is provided a switch having a moving contact made slidable with respect to stationary contacts mounted on a pole board, wherein the pole board is provided with insulator portions of an insulator having sliding faces on their surfaces which are so protruded from the pole board as to correspond to ON/OFF switching positions for providing contact/non-contact boundaries of sliding motions of the moving contact with respect to the stationary contacts; the insulator portions are provided in their sliding faces with recesses which correspond to the OFF positions of the moving contact for reducing facial pressures; and when the moving contact slides with respect to the stationary contacts to the ON/OFF switching positions of the stationary contacts, the moving contact starts to ride on the sliding faces of the insulator portions so that the moving contact goes out of contact with the stationary contacts and can move from the sliding faces into the recesses, and when the moving contact goes down the sliding faces of the insulator portions, the moving contact contacts with the ON/OFF switching positions of the stationary contact.
According to a second aspect of the invention, there is provided a switch comprising a pole board having stationary contacts; and a moving board including a moving contact made slidable to the stationary contacts and made movable with respect to the pole board, whereby the switch detects the shift position of an automatic transmission with the moving contact and the stationary contacts, wherein the pole board is provided with insulator portions of an insulator having sliding faces on their surfaces which are so protruded from the pole board as to correspond to ON/OFF switching positions for providing contact/non-contact boundaries of sliding motions of the moving contact with respect to the stationary contacts; the insulator portions are provided in their sliding faces with recesses which correspond to the OFF positions of the moving contact for reducing facial pressures; and when the moving contact slides with respect to the stationary contacts to the ON/OFF switching positions of the stationary contacts, the moving contact starts to ride on the sliding faces of the insulator portions so that the moving contact goes out of contact with the stationary contacts and can move from the sliding faces into the recesses, and when the moving contact goes down the sliding faces of the insulator portions, the moving contact contacts with the ON/OFF switching positions of the stationary contact.
In a switch as set forth in the first or second aspect of the invention, according to a third aspect of the invention, the recesses have a depth set equal to or more than the distance between the sliding faces of the insulator portions and the surfaces of the stationary contacts.
In a switch as set forth in the first or second aspect of the invention, according to a fourth aspect of the invention, the moving contact is provided with a contact portion for contacting with the stationary contacts and a riding portion capable of riding on the insulator portions; and when the contact portion slides with respect to the stationary contacts to the ON/OFF switching positions of the stationary contacts, the riding portion starts to ride on the sliding faces of the insulator portions so that the contact portion goes out of contact with the stationary contacts and so that the riding portion can move from the sliding faces into the recesses, and when the riding portion goes down the sliding faces of the insulator portions, the contact portion contacts with the ON/OFF switching positions of the stationary contact.
In a switch as set forth in the fourth aspect of the invention, according to a fifth aspect of the invention, the recess has a depth smaller than the distance, as formed when the riding portion rides on the sliding faces of the insulator portions, between the contact portion and the stationary contacts.
According to the first aspect of the invention, there is provided a switch having a moving contact made slidable with respect to stationary contacts mounted on a pole board, and the pole board is provided with insulator portions of an insulator having sliding faces on their surfaces which are so protruded from the pole board as to correspond to ON/OFF switching positions for providing contact/non-contact boundaries of sliding motions of the moving contact with respect to the stationary contacts. When the moving contact slides with respect to the stationary contacts to the ON/OFF switching positions of the stationary contacts, therefore, the moving contact starts to ride on the sliding faces of the insulator portions so that the moving contact goes out of contact with the stationary contacts. When the moving contact goes down the sliding faces of the insulator portions, the moving contact can contact with the ON/OFF switching positions of the stationary contact.
When the riding portion of the moving contact rides on the insulator portion or goes down the insulator portion irrespective of the position of the end edge of the stationary contact, therefore, the moving contact can be reliably into contact/non-contact at the ON/OFF switching position over the stationary contacts. As a result, it is possible to detect the shift position accurately.
Moreover, the insulator portions are provided in their sliding faces with recesses which correspond to the OFF positions of the moving contact for reducing facial pressures. Therefore, the moving contact can move from the sliding faces into the recesses to lower the facial pressure of the moving contact drastically in the OFF state. Even when the moving contact slides in the OFF state, therefore, it can slide in the state of a low facial pressure in the recesses to suppress the wear of the moving contact drastically. As a result, the mechanical position of the moving contact and the contact switching position can be kept long in the initial setting without being offset, to improve the durability of the switch drastically.
Moreover, the wear reduction at the insulator portion can suppress production of the abrasion powder so that the abrasion powder of the insulator does not move or hardly moves together with the moving contact onto the station contacts when the moving contact goes down onto the stationary contacts, thereby preventing contact failure when the moving contact is brought down onto the stationary contacts.
According to the second aspect of the invention, a switch comprises a pole board having stationary contacts; and a moving board including a moving contact made slidable to the stationary contacts and made movable with respect to the pole board, whereby the switch detects the shift position of an automatic transmission with the moving contact and the stationary contacts. The pole board is provided with insulator portions of an insulator having sliding faces on their surfaces which are so protruded from the pole board as to correspond to ON/OFF switching positions for providing contact/non-contact boundaries of sliding motions of the moving contact with respect to the stationary contacts, and the insulator portions are provided in their sliding faces with recesses which correspond to the OFF positions of the moving contact for reducing facial pressures. Therefore, effects similar to those of Claim 1 can be attained in the switch for detecting the shift position of the automatic transmission.
In addition to the effects of the first or second aspect of the invention, according to the third aspect of the invention, the recesses have a depth set equal to or more than the distance between the sliding faces of the insulator portions and the surfaces of the stationary contacts. Therefore, the facial pressure of the moving contact can be reliably lightened.
In addition to the effects of the first or second aspect of the invention, according to the fourth aspect of the invention, the moving contact is provided with a contact portion for contacting with the stationary contacts and a riding portion capable of riding on the insulator portions. Therefore, the slides of both the contact portion and the riding portion can be shared between the stationary contact and the insulator portions so that their wears can be more lightened.
In addition to the effects of the fourth aspect of the invention, according to the fifth aspect of the invention, the recess has a depth smaller than the distance, as formed when the riding portion rides on the sliding faces of the insulator portions, between the moving contact and the stationary contacts. When the riding portion rides on the sliding faces of the insulator portions, therefore, the facial pressure of the contact portion of the moving contact can be reduced to zero thereby to lighten the wear more.